In recent years, an optical disk as a recording medium of a recording and reproducing apparatus has had a lot of variations in such as its recording mode and disk diameter. This is because a recording technique, particularly the fact that laser wavelength has been getting shorter from infrared light to red light and blue light, makes it possible to record and reproduce with a capacity having not less than that of a conventional one even in case of smaller disk diameter than the conventional one.
Variations of disk diameter will be described. For example, as to a compact disk (CD) not having a cartridge, both CDs having disk diameters of 8 cm and 12 cm were easily interchangeable in the same drive. However, since most of recording media were contained within the cartridge in terms of reliability, it was difficult to record and reproduce disk cartridges having different disk diameters in the same recording and reproducing apparatus.
For example, there is a mini disk (MD) as a typical recording medium contained within a cartridge. Since recording media having different disk diameters were not assumed according to the specification of the mini disk, any problem did not arise.
The following will describe the CD apparatus as described above, and a mini disk (MD) apparatus as a typical recording and reproducing apparatus having a magnetic head.
First, as shown in FIG. 18, only if a disk 201 can be loaded in a CD apparatus 200, recording media having different disk diameters do not cause a problem especially in terms of interchangeability because a cartridge does not exist. As is apparent from FIG. 18, even if a pickup housing 202 moves to the outer periphery of the disk 201, no interference between members occurs.
On the other hand, as shown in FIG. 19, a MD apparatus 300 has the arrangement such that a magneto-optical disk 301 gets caught between (a) a pickup housing 302 including an optical pickup (not shown) which projects laser light and (b) a slider 303 including a magnetic head 304 which moves in accordance with laser spotting points. By reversing the direction of a magnetic field generated by the magnetic head 304 in accordance with recording signals, signals are recorded on the magneto-optical disk 301.
Further, the slider 303 including the magnetic head 304 is movable, following a surface shaking of the magneto-optical disk 301, dust, protuberance, and the others on the magneto-optical disk 301. Thus, the magneto-optical disk 301 is prestressed at 3 mN to 10 mN by a suspension 305 which is made up of thin metal in a thickness of 30 μm to 100 μm. In addition, one end of the suspension 305 is secured so as to be fixed to a magnetic head arm 306.
An extreme proximity of the magnetic head 304 to the sliding surface of the disk makes it possible to record on the magneto-optical disk 301. If the magnetic head 304 is allowed to be away so as to jump out of the cartridge 307, recording is impossible. The magnetic head 304 is connected to the pickup housing 302 through the magnetic head arm 306 which is horseshoe-shaped. Thus, the pickup housing 302 and the magnetic head 304 are arranged so as to move radially by a pickup feeding mechanism 308 connected with the pickup housing 302 with elements such as screws or gears to drive.
The magnetic head 304, which is called a sliding-type magnetic head, is now used generally in the MD apparatus. Note that, there are also many MD apparatuses in which the magnetic head 304 is lifted up from the inside of the cartridge 307 since the magnetic head 304 is not required in reproducing.
Incidentally, the arrangement is also adopted in many MD apparatuses such that an objective lens 309, which is a part of the optical pickup, is incorporated to the cartridge 307 in order to focus a laser beam. In the case, it is necessary to pay attention to the crash of the cartridge 307 and the objective lens 309 at the time when the pickup housing 302 runs out of control.
For example, as is apparent from FIG. 20, there is the danger that a crash of the slider 303 having the objective lens 309, the suspension 305, and the magnetic head 304 occurs at the periphery of the cartridge 307 when the optical pickup is positioned in the vicinity of the outer most periphery of the magneto-optical disk 301.
Thus, in case where the cartridge 307 containing the magneto-optical disk 301 and a magnetic head 304 of contacting and sliding-type are used for recording, each of the objective lens 309, the suspension 305, and the slider 303 crashes with the cartridge 307 if the movement of the optical pickup excesses the disk diameter of the magneto-optical disk 301. Accordingly, the damage to the magnetic head 304 and the optical pickup is unavoidable. Therefore, in the MD apparatus 300, a housing stopper 310 is generally provided so that the pickup housing 302 cannot move to more the periphery than necessary.
As described before, since in the MD apparatus 300, the objective lens 309 or the slider 303 may crash with the cartridge 307, the housing stopper 310 is generally provided to prevent the crash.
Incidentally, optical disks having various diameters have been in the market in recent years. Use of the same drive device for these optical disks can be realized only in the player which reproduces CDs that do not use cartridges.
Now, with respect to the problem, assuming that disk media having different disk diameter contained in cartridges are recorded and reproduced in a drive device capable of recording and reproducing with a spindle and a single optical pickup, the movable distance of the optical pickup varies depending on respective maximum disk diameters. Therefore, a disk recording and reproducing apparatus, which reproduces with respect to a disk having maximum diameter contained in a cartridge for maximum disk diameter, has a problem that reproduction of a disk having a smaller diameter contained in a cartridge occurs the damage to a suspension for a magnetic head if no measure is taken for the case when the optical pickup runs out of control. Conversely, if the magnetic head is lifted up at the outer periphery so as not to crash with the cartridge in order to solve the above problem, recording in the outer periphery of the disk media having maximum diameter is impossible.
Further, recently there have been some disk recording and reproducing apparatuses which have an arrangement such that a part of an optical pickup is incorporated to a cartridge. The disk recording and reproducing apparatuses of the type have a problem that if disk media having different disk diameters is recorded and reproduced, not a magnetic head, but a part of the optical pickup, for example, an objective lens, or a part of an actuator crashes with the cartridge, thereby causing the damage to a drive apparatus.
That is, it is understandable that both the optical pickup and the magnetic head may damage when the optical pickup runs out of control in the disk recording and reproducing apparatus which secures an interchangeability for the recording media having different disk diameters inserted to the respective cartridges, especially in the state that media with a smaller diameter are loaded to the apparatus.
Further, the disk recording and reproducing apparatus, which is configured so as to use recording media not having cartridges like conventional CDs, is comparatively easy to be available for the disks with different diameters. However, it is a big problem that reliability in recording and reproducing declines by dirt such as dust and finger prints on the surface of the recording media.